Prototype HTTP Otel Semantic convention stability opt-in

[lzchen]

As part of the effort to mark http semantic conventions as stable Python has volunteered to provide a http client and server instrumentation prototype. These prototypes will implement the migration plan for http instrumentations to be updated to follow the latest semantic conventions. Since v.1.21.0 has been merged in the core repo, we can begin implementing the migration plan with two instrumentations. The work involves:

1. Deriving a mechanism in which we will control the opt-in
2. Prototyping a http client instrumentation
3. Prototyping a http server instrumentation

Part of #1768

[lzchen]

Superseded by: #2453